Simple copypaste became the reason of interesting debug story :)

Fuckup.m

+ (UIImage *)generatedBackground {
    static NSArray *colors = nil;
    if (!colors) {
        colors = @[
                [UIColor colorWithRed:0.957 green:0.138 blue:0.287 alpha:1.000],
                ...
                [UIColor colorWithRed:0.972 green:0.207 blue:0.225 alpha:1.000],

        ];
    }

    UIImage *overlay      = [UIImage imageNamed:@"backgroundRoundOverlay"];
    UIImage *heavyOverlay = [UIImage imageNamed:@"heavyBackgroundOverlay"];

    UIImage *image = nil;
    UIGraphicsBeginImageContextWithOptions(overlay.size, YES, .0);
    {
        [colors[arc4random() % colors.count] setFill];
        [[UIBezierPath bezierPathWithRect:(CGRect) {CGPointZero, overlay.size}] fill];
        [overlay drawAtPoint:CGPointZero];
        [heavyOverlay drawAtPoint:CGPointZero blendMode:kCGBlendModeNormal alpha:.3];
        image = UIGraphicsGetImageFromCurrentImageContext();
    }
    
    UIGraphicsGetImageFromCurrentImageContext(); // <<- ooops, UIGraphicsEndImageContext intendent call
    
    return image;
}